【作者】 杨潇；

【导师】 陈吉华； 张凌； 王辉；

【作者基本信息】 第四军医大学 ， 口腔临床医学， 2010， 硕士

【摘要】 树脂水门汀因其卓越的机械、物理、粘接性能以及美学效果,在临床上的应用日趋广泛。树脂水门汀依其固化方式可分为三类:自固化(化学固化)、光固化及双固化型树脂水门汀。光固化树脂水门汀常被用于粘接瓷或者复合树脂修复体。将这些修复体就位并光照时,修复材料会对光线进行吸收、折射或反射,光的强度减弱,使得树脂转化率(degree of conversion, DC)降低以及并造成大量C=C残留。较低的转化率将会导致树脂的强度、硬度减弱,颜色稳定性变差,树脂溶解性上升,影响树脂的生物学性能。未固化树脂其细胞毒性也大大高于已固化的树脂。为了解决光固化树脂水门汀因可接受到光能有限导致固化不全带来的一系列临床问题,双固化水门汀应运而生。双固化树脂水门汀可以在对其光照后,又发生自固化来弥补仅由单纯光固化引起的固化不全问题。然而,自双固化树脂水门汀上市后,众多实验研究结果表明,对双固化树脂水门汀若不进行光照,其转化率会大大降低,且没有足够实验研究依据证明对双固化树脂水门汀进行光照后,又会发生大量化学固化。双固化树脂水门汀的固化方式,也可能会对其转化率造成影响。本研究旨在比较光照、不光照、延长光照时间及软启动光照对临床上常用的两种双固化型树脂水门汀PANAVIA F(PF)及Clearfil SA-LUTING(SA)的影响。实验一研究了光照对双固化树脂水门汀固化性能的影响。实验选取了20min、24h和1mo.作为3个观察期。实验结果显示:①20min内,不光照的两种水门汀材料均未发生固化;光照20s的条件下,PF组转化率恒定不变,而SA组转化率逐渐增加;在每个观测点,SA组的转化率均高于PF组;②24 h内,两种材料的转化率随时间上升;③1mo.内,两种材料的转化率值均随时间上升,24h后上升较为平缓;④每个观测时间点,光照组的转化率均高于不光照组。实验二研究了延长光照时间对双固化树脂水门汀固化性能的影响。实验结果显示:①20 min内,PF组光照20s及光照40s的转化率基本保持恒定不变;光照60s组的转化率随时间缓慢上升;SA组光照20s、40s、60s的转化率均随时间上升;②24 h内,两种材料的转化率值随时间上升;③1mo.内,两种材料的转化率值也随时间上升,24h后上升较平缓;④对同一种材料而言,延长光照时间可显著提高其转化率。实验三研究软启动光照对双固化树脂水门汀转化率的作用。实验结果显示:①各组20 min、24h、1mo.内的转化率均随时间上升;②相同处理条件下,SA组的转化率均高于PF组;③对同一材料在同一观测点,软启动光照组的转化率值低于正常光照组。综上所述,我们可以得出以下结论:一、光照是双固化树脂水门汀固化的始动因素。如不对双固化树脂水门汀进行光照,则其在固化初期不会发生聚合反应。不光照组虽然在20min后仍有固化反应发生,但从整个固化过程来看,不光照组的转化率一直低于光照组。因此,临床上应用双固化树脂水门汀时,还是应该对其进行光照以激发并最大程度地促进其固化反应。二、光照时间会对双固化树脂水门汀的转化率会产生影响。从整个实验过程来看,延长对双固化树脂水门汀的光照时间,可以大大提高其转化率。双固化树脂固化60s,可以使树脂在固化初期即发生较为完全的固化。因此,60s也是本实验推荐的光照时间。三、光照强度会影响到双固化树脂水门汀的转化率。采用软启动光照方式,树脂所接受到的光照强度要低于普通光照方式,会导致树脂水门汀的固化不完全,影响到树脂水门汀的转化率。因此,若单纯从转化率考虑,临床上并不建议对双固化型树脂水门汀采用软启动固化的固化方式。更多还原

【Abstract】 Up to now, resin luting cements are so popularly used in clinic, due to the remarkable mechanical, physical and bonding properties, and the excellent esthetic effects. Resin luting cement can be divided into three kinds according to the curing modes:self-cured (chemical cured), light cured, and dual cured resin (light cured & chemical cured) cement. Light cured resin cement can be used for bonding ceramic or composite restoratives. When the restoratives are seated and then light cured, the light intensity can be attenuated by the restorative materials, and the degree of conversion of resin cement will be reduced and large amount of unconverted "c=c" will be residual. Low degree of conversion can lead to weakness of strength and hardness and the lower color stability of resin luting cement, and can causing high solubility, and disturbing the biological properties. The cytotoxicity of uncured resin luting cement will be more severe than the cured ones. To solve all the problems cause by insufficient cure of light cured resin cements, dual cured resin luting cements were introduced. After light curing to the dual-cured resin luting cement, the self-curing will also be generated and thus compensate the insufficient curing caused by light curing only. However, previous studies has confirmed that if the dual cured resin luting cement is not light cured, the degree of conversion will reduced. But, there is no evidence to support the theory that large quality of chemical curing can occur after light curing. And it is uncertain whether the curing method would affect the degree of conversion.The purpose of this present study was to examine the effects of light curing, prolonged curing time and soft-started curing mode on the degree of conversion (DC) of two dual-cured resin luting cements: Panavia F & Clearfil SA-LUTING resin cement.In experiment 1, the effect of light curing on the polymerization properties of dual-cured resin cements has been evaluated. The observation periods were selected as 20min, 24h and 1mo.. We could obtain the results as the following:①Within 20min, the two tested materials without light curing didn’t cured; without light curing, the DC of PF group was unchanged, and that of SA group increased slowly;②Within 24hs, the DC of two materials increased with time;③Within 1 month, the DC of two materials increased with time, and after 24hs, the trend of DC increased gently;④For every time tip, the DC of SA was higher than that of PF, and DC of light cured group was higher than the group without light curing.In experiment 2, the effect of prolonged light curing on the DC was observed. The results showed that:①Within 20min, the DC of PF groups of light cured for 20s and 40s groups could increase quickly at the beginning and kept in flat later, the DC of group being light cured for 60s increased slowly; and for SA group, when light cured for 20s, 40s and 60s, its DC raised slowly;②within 24hs, the DC of two materials increased with time;③within 1mo., the DC of two materials increased with time, and the DC increased gently after 24hs;④for the same material, prolonged curing time could increase the DC significantly.In experiment 3, the effect of soft-started light curing on the DC was determined. The results showed that:①for both the materials, within 20min, 24h and 1mo., the DC increased with time;②with the same treatment, the DC of SA was higher than that of PF;③In the same observation tip, the DC of soft-started group was higher than that of the normally cured group regardless of the type of the cement.According to the results from this present study, we could draw the conclusions as the following:1. Light curing should be one initiator of the curing process of dual-cured resin cement. If the dual-cured resin cement was not exposed to light irradiation, no polymerization would be induced during the polymerization process. For groups with no light irradiation, although polymerization happened after 20min, the DC of light cured groups were higher than the groups without light curing during all the curing process. Thus, light curing should be provided to the dual-cured resin cement to activate and promote the reaction of polymerization.2. Light curing time might affect the DC of resin cement. Among all the observing period, prolonging the curing time could increase the DC. And for group with 60s’light curing, the polymerization at the first period could go to the pit quickly. Thus, 60s is the recommended curing time from this study. 3. The light intensity can affect the DC of dual-cured resin cement. In soft-started light curing group, the light intensity received was lower than that of normally cured group and would affect the DC of the resin cement. So, considering the complete DC of dual-cured resin cement, the soft-started curing mode sould not be recommended to the clinic.更多还原